JPS62195733A - Track detection circuit - Google Patents

Abstract

PURPOSE:To obtain a high speed program search by identifying an interval between tracks of an optical disc depending on the length of an inverting time of data being the result of read by an optical pickup from the data written on the optical disc so as to obtain a correct track loss signal even when the optical pickup is moved at a high speed. CONSTITUTION:In converting a high frequency reproducing signal from a photodetector 1 by a comparator 4 into a pulse, since a reference voltage VREF is fed to the comparator 4, a pulse signal is obtained. The reference voltage VREF of the comparator 4 is arranged nearly at the center of a track zero cross envelope (x) of a high frequency reproducing signal HF including the DC component and the separated pulse goes to a pulse train comprising a track part consisting of a carrier component and a long inverted part being a mirror face part between tracks. The output is supplied to a pulse length deciding circuit 6, a circuit generating a signal when a prescribed length or over of pulse interval exists is provided and the signal is extracted as a track cross signal.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a rack detection circuit used in an original disk storage device, and in particular to a signal track detection circuit when the original disk is quickly accessed by the original pickup. With Kancho. When reading out a source disc such as a compact disc or video disc, if you search for a predetermined position, select a predetermined position from the current position of the original pickup. Move the original pickup up to t. At this time, the amount of movement of the original pickup is determined by counting the number of tracks on the disk (t) to determine the distance to the target position, and detecting the rate of movement of the original pickup based on the frequency of the track count, that is, the amount of movement per unit time. Prefecture. For this reason, this truck detection circuit is very important in moving the original pickup quickly and finding the target truck meeting, and improvements in these circuits are desired.

[Conventional technology]

The track cross of the original pickup source spot is described in detail with respect to the detector and its waveform diagram in Figure 5 of the conventional circuit in Figure 6. In FIG. 5, the reflected red spot of the spot projected onto the original disk is picked up by a photodetector such as a pin photodiode, and amplified by a photodetector 42. @ High frequency reproduction signal (HF) as shown in Figure 6 (a) [I J k In addition to the low pass Fv filter (LPF) 3, as shown in Figure 6 (b), the partial output waveform The average reflection level difference between the information part on the track and the part between the tracks is separated by 7, and in addition to this output comparator 4, it is compared with the reference direct pressure VREF. The pulse waveform shown in Figure (C) was obtained.

[Z problem when the invention is decided]

When the original pickup is moved at high speed in the width direction of the disk using the conventional configuration of narrowing, the track cross frequency increases by 4 degrees. Therefore, it is necessary to adjust the cutoff frequency of the LPF3. Since the in-track information "i" shown in No. 61 0) contains a modulated signal, it includes sideband energy etc. in addition to the carrier, and -1-carrier frequency and track cross frequency <' = o Separate this part n
As shown in the part hidden pressure i1 in Figure 6 (b), S/
The track cross pulse that passed through the conhalator 4 due to deterioration of N is as shown in r fit J in Figure 6 (c).
(There was a drawback that the correct IA number could not be obtained because it was disturbed by the noise of the +1 wave, and there was a limit to the ability to move at high speed in the width direction of the original big-up key C disk. Also, the detector circuit was complicated. There was a stone defect.

[Means for Solving Skin Discs for 1 and 4] The present invention was made in view of the drawbacks of constriction, and its purpose is to move the optical pickup disc in the width direction at a higher speed than before. However, it is difficult to obtain a track detection device that can detect the correct track number. And the way to do that is to put T! on the original disc! Depending on the length of the reversal time of the data read out by the 7-source pickup, the tracks on the optical disc can be identified by an identifier 2.
In the present invention, the reflected signal from the disk is added to the comparator without integration, and the track and track opening are separated by the pulse interval of this inverted signal. Later with things. That is, u
'We focused on the maximum interval between pits in the Jfn signal and the alignment of the signals between tracks, and based on these differences, we set the trough No. 418 to A.

〔Example〕

The following is the +invention of the trucky circuit 11.

, 'g1 Figure θ shows a system diagram of the track single bundle output circuit of the present invention.
b)) Pulsed by all comparators 4. A reference voltage VRIF is applied to the comparator 4.
Therefore, the pulse 1 word obtained as shown in Fig. 2 (b) is A.

At this time, the reference voltage vRgr of the comparator 4 is set approximately at the center of the track zero cross envelope X of the high frequency reproduction signal HF (FIG. 2M) containing the DC component 7, tN. As shown in Figure 2 (b), the pulses separated by this are separated into a track part consisting of a carrier component, a mirror surface part between the tracks, and a long part of inversion between the tracks, resulting in a missing pulse train. .

The output r is input to the pulse length judgment circuit 6, and the circuit configuration that generates a signal when the pulse interval is longer than a predetermined value is output as a track cross signal as shown in FIG. 2(c).

Here, the pulse length determination circuit 6 may be a retriggerable monostaple multipibrator or the like. Regarding this, first of all, the distance I'm included in the data is 3T to IIT in the example of a compact disc.
1 The maximum width is IIT, and the clock of T is approximately 4.2 M
HZ and approximately 4.4μB is the maximum pulse. First, as shown in FIG. 3, the data shown in FIG. 21(B) is slightly delayed by a delay line 6a. This tL is the trigger pulse of the multivibrator.4 *It is sufficient that this kind of operation is possible, and it may take several microseconds to several microseconds. In addition to this signal all exclusive OR circuit 6a, as shown in FIG.
C)'s standing blade, standing blade's Eragino Kurusuke Kotobuki. This pulse triggers and staves the retriggerable monostaple vibrator 6C.

Here, the trigger pulse width t' of the monostable multipipe rake is larger than 4.4μB of 11T during the previous maximum pulse. The pipe rake 6c continues to operate.The pulse interval is the set pulse t.
If the monostable multi-pipe rake is larger, it will be restored to its original state.4o This will cause even the discrimination to be equivalent to 1'+ until the pulse interval at the interface part where there is no information between the two tracks approaches 11T4o. is necessarily a simple 4-component signal, and therefore the sideband of the carrier may extend even below 10 KHz, so generally the track cross signal is 10 KHz-@
It was rare that the sensor could be stably detected at the limit of 4. In contrast to 1), in this application, even if t is set to twice the maximum pulse IIT, 1
If it becomes 13KHZ and further tightened to t', the limit is 1-12.
00 K H2 and 'z is 10 times the conventional value 1j iJj
Track detection is possible up to

In addition, in the implementation of Figure 1, the reference direct pressure VREF k of the comparator 4 was fixed, but the high frequency reproduction signal (Figure 2 (a)
) is detected by the peak level detector 7, and this +"jL HE k is detected as the pressure VoF.
By adding it with the F adder 8 and changing it to the reference mixed pressure VREF, it becomes stable against disc variations, etc., and the level changes due to track cross can always be taken correctly. . Here, the high frequency (") raw signal is No. HF4-1) Rack error 1 No. 3 The signal corresponding to the edge beam such as the beam is taken out, and the carrier component is also taken out from the center detector. But it's funny. Also, in the HF l row after AC

〔Effect of the invention〕

The present invention has been made to operate as if it were a work of art, so even if the original pickup is moved quickly, the correct track cross signal is maintained using a simple circuit. Z Koto's performance and CD are ;↓.

4. 1′ of the drawing! Simple explanation No. 11 is a systematic diagram of the track detection circuit of the present invention, 5-2
(' In the conventional track detection circuit system, rn 61= is the fifth
In the waveform diagram shown in the figure 4.
Φ・Pulse length judgment circuit 5B**a delay 6b...
Exclusive OR circuit 6c fist...Mono Stagle Multi Piper 7...
Peak level detector 8・φ・J, +v 14?3 2nd
j 31J Fig. 4

Claims (2)

[Claims] (1) A track detection circuit characterized in that the tracks of the optical disc are distinguished from each other by the length of the inversion time of the data read out by an optical pickup from the data written on the optical disc. (2) The track detection circuit according to claim 1, wherein the optical pickup uses the signal for identifying the track and the track as a track cross signal of the optical disc.